The purpose of my research is to study some of the anatomical and physiological mechanisms that influence the recovery of function that follows traumatic brain injury. I am currently examining how "neurotrophic" substances facilitate behavioral recovery from brain injury in animals of different ages. In one series of experiments, intracerebral injections of nerve growth factor (NGF) enhanced the rate of recovery in rats with lesions of the caudate nucleus or the substantia nigra; both regions are implicated in motor activity and arousal. In another project, I am examining some of the neuromorphological consequences of NGF injections and find that NGF enhances the growth and differentiation of reactive astrocytes in the brain which in turn, may provide the milieu required for the remaining intact neurons to compensate for injury. To provide baseline data, I have had to examine age-related atrophy in the CNS as well as compensatory hypertrophy in brain damage subjects. In brief, there is considerable neuronal loss in brain and spinal cord of aged rats. Future studies will examine whether neurotrophic substances can alternate the loss, facilitate "sprouting" of neurons and reduce concomitant behavioral deficits.